Miraskar, Rekha (2018) Regulation of angiogenic growth factors (sFLT-1 and PLGF) by CRH family of peptides under altered oxygen tension in trophoblast and endothelial cells. PhD thesis, University of Warwick.

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Abstract

Preeclampsia, a pregnancy specific vascular disorder, is one of the leading causes of maternal and fetal morbidity and mortality worldwide. Abnormal placental angiogenesis resulting from altered levels of angiogenesis regulators, such as soluble fms-like tyrosine kinase (sFLT-1), vascular endothelial growth factor (VEGF) and placental growth factor (PLGF) has been implicated to be central in the pathophysiology of preeclampsia. sFLT-1 and PLGF have been recently proposed as one of the potential biomarkers to aid in the clinical diagnosis and prediction of preeclampsia. However, the molecular mechanisms underlying placental dysregulation of angiogenic molecules leading to endothelial dysfunction in preeclampsia remains as an enigma. Along with sFLT-1, factors such as corticotrophin releasing hormone (CRH) and cortisol that are secreted by placenta are elevated in serum of preeclamptic women. Recent studies have illustrated a cardinal role of the CRH family of peptides in the regulation of VEGF in various cells. Accumulating evidence suggests a mechanistic association between CRH related peptides and regulators of angiogenesis. Thus, this project aims to investigate their interactions in trophoblast and endothelial cells and establish a potential link between their signaling pathways, using in vitro models under altered oxygen tension. This project will also focus effect of SFLT-1 rich media on fusogenic machinery and endocrine capacity of BEWO cells under altered oxygen tension.

Using various techniques (western blot, ECLIA, QRT PCR, ELISA and MSD human angiogenesis panel assay), my preliminary data from BEWO and HUVECs cellular models showed that CRH related peptides probably regulates sFLT-1 and PLGF protein secretion in HUVECs, HTR8/SVneo cells but not in BEWO cells. In HTR8 cells, CRH has no effect on sFLT-1 transcription under normal and low oxygen tension, but increases sFLT-1 release under low oxygen tension. Under altered oxygen tension, CRH increases VEGF mRNA more compared to PLGF mRNA. a trend towards an increase in PLGF release by CRH is seen. CRH regulates angiogenic factors in trophoblasts under altered oxygen tension. CRH possibly favors angiogenic state under low oxygen tension at the transcription level, although CRH appears to increase sFLT-1/PLGF ratio at protein secretion level. Hypoxia increases CRHR1 and decreases CRHR2 transcription. CRH decreases transcription at CRHR1 and CRHR2 mRNA under high oxygen tension. CRH reduces hypoxia induced upregulation of CRHR1 but not CRHR2 mRNA.

CRH was unable reverse hypoxia mediated impaired fusogenic machinery and biochemical differentiation in BEWO cells and unable to restore the syncytialization. Hypoxia increases CRHR1 and CRHR2 expression in BEWO cells. CRHR2 more predominately being expressed than CRHR1 in hypoxia. CRHRs are differentially regulated in syncytialised BEWO cells under altered oxygen tension. CRH blocks upregulation of CRHR1 gene expression in differentiated BEWO cells under high oxygen tension. CRH blocks CRHR1 in undifferentiated BEWO cells under low oxygen tension. CRHR1 is down regulated in syncytialised BEWO cells when exposed to altered oxygen tension. CRH when added to differentiating cells under low oxygen tension has no effect on its receptors. Moreover, sFLT-1 rich media mediates fusogenic machinery and under low oxygen tension. CRH further impairs this and CRHR1 is down regulated which is reversed under low oxygen tension.

Preliminary data from BEWO and HUVECs cellular models showed that CRH related peptides probably regulate sFLT-1 and PLGF protein secretion in HUVECs and HTR8/SVneo cells, but not in BEWO cells; CRH’s effect varies in altered oxygen conditions. CRH possibly favors angiogenic state under low oxygen tension at the transcription level, although CRH appears to increase sFLT-1/PLGF ratio at protein secretion level. CRH was unable reverse hypoxia mediated impaired fusogenic machinery and biochemical differentiation in BEWO cells and unable to restore the syncytialization. When added to differentiating cells under low oxygen tension, CRH has no effect on its receptors. Moreover, sFLT-1 rich media mediates fusogenic machinery under low oxygen tension. CRH further impairs this and CRHR1 is downregulated which is reversed under low oxygen tension. The next step in research should focus on assessing the regulation of SFLT-1 and PLGF at transcriptional, translational and secretion level under altered oxygen tension and confirm the involvement of CRHRs in regulation of angiogenic and anti angiogenic factors.

Item Type:	Thesis or Dissertation (PhD)
Subjects:	Q Science > QP Physiology R Medicine > RG Gynecology and obstetrics
Library of Congress Subject Headings (LCSH):	Preeclampsia, Vascular endothelial growth factors, Blood-vessels -- Growth, Corticotropin releasing hormone, Peptide hormones
Official Date:	September 2018
Dates:	Date Event September 2018 UNSPECIFIED
Institution:	University of Warwick
Theses Department:	Warwick Medical School
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Grammatopoulos, Dimitris
Format of File:	pdf
Extent:	409 leaves : illustrations
Language:	eng

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